Sonic machine for cutting pavement



Feb. 1, 1966 A. G- BODINE, JR 3,232,669

SONIC MACHINE FOR CUTTING PAVEMENT Tiled May 5, 1962 s Sheets-Sheet 1 42| 5) 'INVENTOR.

ATTORNY ALBERT G. BODINE JR.

Feb. 1, 1966 Filed May 5, 1962 FIG. 2

A. G- BODINE, JR

3 Sheets-Sheet 2 L l' l g T INVENTOR. ALBERT G. BODINE JR. BY/ 4 ATTORNEY Feb. 1, 1966 A. G. BODINE, JR 3,232,659

SONIC MACHINE FOR CUTTING PAVEMENT *siled May 5, 1962 3 Sheets-Sheet 5 8 5 3 3'3 Q;

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'INVENTOR.

ALBERT G. BODINE JR.

ATTORNEY United States Patent O 3,232,669 SONIC MACHINE FQR CUTTING PAVEMENT Albert G. Bodine, .lra, Los Angeles, Calif. (7877 Woodley Ave., Van Nuys, Calif.) Filed May 3, 1962, Ser. No. 192,232 Claims. (Cl. 299-37) This invention relates generally to sonic machines for cutting or ripping road or yard pavement, particularly asphalt or concrete pavement of a few inches in thickness, and intended and designed especially for use in cutting a long slot in the pavement preparatory to the digging of a trench in the ground underneath.

Reference is made to my prior and copending application Serial No. 163,802, filed January 2, 1962, which was a division of my original application Serial No. 839,196, filed September 10, 1959 (now Patent No. 3,030,715).

At the present time, paving is usually cut or broken either by hand-held pneumatic jack hammers, or by means of a heavy weight carried by a vehicle, and which is alternately hoisted and dropped on the paving as the vehicle slowly inches forward. The former are successfully used, but are noisy, involve diflicult manual labor, and are slow in performing the job; while the latter are productive of very bothersome noise and vibration, and may not form a good, uniformly defined slot.

A primary object of the invention is accordingly to provide a vehicle-mounted sonic vibratory machine capable of cutting a uniformly defined slot in paving, with material decrease in noise, and with materially increased speed and facility.

In accordance with the invention, speaking broadly, there is provided a relatively heavy elastic vibratory structure, capable of being driven to vibrate at a resonant frequency which will develop a standing wave therein. This vibratory structure is vehicle-mounted, and arranged so that a vibratory portion thereof is engageable with an exposed edge of the paving which is to be ripped or slotted. The elastic vibratory structure may be in any one of several feasible configurations, a practical example of which comprises an elongated bar; and a bar type of vibratory member may be variously oriented and configured. For example, the bar may be disposed vertically or horizontally and transversely of the vehicle, in either of which cases it will be excited to vibrate in a lateral standing wave mode of vibration. Or, it may be disposed longitudinally of the vehicle, and be provided with a coupling face or shoulder near or at one of its ends; and in such case the bar may be excited to develop a longitudinal standing wave mode of vibration.

The preferred form of the invention, specifically illustrated and described herein, has the bar in a vertical position at the rear of atractor vehicle, and excited to vibrate in a lateral standing wave mode of vibration. A side surface of the bar, near the lower end of the bar, couples the sonic wave action into the exposed edge of the paving. The coupling surface is preferably provided with effective pavement cutting or breaking formations, such at teeth. The bar, vibrating in a lateral standing wave mode, causes this toothed or serrated coupling face to work against the edge of the paving. The paving, subject to the resulting repetitive stress, breaks up readily; and the vehicle, moving slowly but steadily forward, cuts a slot in the paving as it travels along. As a preferred added feature-one which is deemed to be very important to maximum performance of the rriachinethe vibratory bar is alternately elevated and lowered during the process through a suflicient distance to constantly give the coupling face formations new surface to work against.

The invention will be better understood from the following detailed description of a present preferred embodiment thereof, reference being bad to the accompanying drawings, wherein:

3,232,659 Patented Feb. 1, 1966 FIG. 1 is a side elevational view of a present preferred and illustrative embodiment of a vehicle-mounted pavement cutting machine in accordance with the invention, parts being broken away to show underlying portions in section, and the view showing also a sonic standing wave diagram representative of the lateral wave action in the elastic vibratory bar of the sonic machine;

FIG. 2 is a plan view of the machine shown in FIG. 1:

FIG. 3 is a vertical sect-ion taken on line 33 of FIG. 2; and

FIG. 4 is a view taken in accordance with line 44 of FIG. 2.

In the drawings numeral 10 designates generally a somewhat diagra'matically illustrate-d tractor vehicle having front wheels 11 and rearwheels 12 supported on the pavement 13 which is to he cut, the pavement 13 being shown as supported by earth 14. The vehicle 10 is provided with a drivers position 15 located somewhat forwardly thereof, and is shown as equipped with seat 16. The vehicle engine, not shown, may be located to the rear of the drivers position and is preferably arranged as far forward of the rear wheel axle as may be necessary to preserve proper balance against the overturning torque of the rear-mounted sonic machine to be presently described.

Vehicle 10 is provided at the rear with a box frame 21 including a bed plate 21, a vertical rearward wall 22-, and side walls 23. To the rear of the rearward wall 22 of this box frame is a mounting block 26, which is formed along its edge nearest the wall 22 with a vertically disposed T-head or slide 27 that is received in the vertically disposed way 30 formed in a guide 31 secured in any suitable manner to the rearward wall 22 of box frame 20. Mounting block 26 is thus arranged for vertical sliding movement with reference to box frame 20, and therefore with reference to the earth.

Mounting block 26 is furnished at the top with a forwardly projecting support bracket 34, to which is secured the upper extremity of a piston shaft 35 extending from a piston 36 is a hydraulic cylinder 37 securely mounted in box frame 2%) adjacent wall 22. Piston 36 can be elevated in cylinder 36 to hoist mounting block 26 and other subsequently described parts mounted on the latter by introducing hydraulic liquid under pressure to the lower end of said cylinder through a pipe 38, and this may be accomplished through the operation of a hydraulic pump conventionally indicated at 39, and which will be understood to receive hydraulic fluid from a suitable source of supply on the vehicle. Suitable valving arrangements may be employed in conjunction with the supply of pressure fluid to the lower end of the hydraulic cylinder in any suitable or conventional manner common in the hydraulic lift art, and therefore not necessary to describe in detail herein. Sufiice it to say that by a suitable control means, the hydraulic piston 36 can be elevated to hoist the mounting block 26 from the working position shown to an inoperative traveling position, or lowered back to the operating position illustrated.

Mounting block 26 is formed with upper and lower pairs of rearwardly projecting ears 40 which receive between them a vertically disposed and generally rectangularly shaped elastically vibratory bar 41, composed preferably of a good grade of steel. Pins 42 projecting through the ears 4% and through the bar 41 mount the bar on the block 26. It will be seen from FIG. 1 that the bar 41 projects downwardly somewhat below lower ear 40, so as to afford a lower end portion capable of engagement with an exposed edge of the pavement 13. It will also be seen that the bar 41 has a portion extending upwardly above the upper ears 40 by a corresponding distance, affording space for mounting 3 of a presently described vibration generator G. There are certain acoustic criteria for the precise location of the cars 40 and mounting pins 42 along the length of the bar 41, and these will be further explained at a later point in the specification.

The lower end portion of the bar is provided on its forwardly facing edge with a coupling face comprised of a plurality of pavement engaging teeth or serrations 44. Preferably, these serrations 44 may comprise teeth nmning horizontally across the full width of the bar, though many varied forms of coupling face formations are of course feasible.

To the forwardly facing edge surface of the upper end portion of bar 41 is secured, as by long screws 46, the housing 47 of a vibration generator G. As will be seen, the generator housing 47 is accommodated just above the upper end of mounting block 26. The generator G is designed to apply to bar 41 a cyclic, laterally or horizontally oriented alternating force side thrust, applied efiectively well above the upper mounting pin 42 of the bar 41. While this generator may be of various types, a preferred form is shown of a class such as disclosed and claimed in my co-pending application entitled, Vibration Generator for Resonant Loads and Sonic Sytsems Embodying Same, filed March 21, 1962, Serial No. 181,385. Other types of vibration generators are capable of use in the invention, but that shown herein, and in a more refined form in said co-pending application, is presently preferred.

With reference now to FIG. 3, generator housing 47 comprises an intermediate body member or block 48 and two end plates 49 and 50, the plate 50 being removed to expose underlying members in FIG. 1. Block 48 has two cylindrical raceway bores 51, one over the other, and each contains an inertia rotor 53. Each such rotor 53 embodies an inertia roller 54 of somewhat less diameter than the corresponding raceway bore, and which is rotably mounted on an axle 55 projecting axially from the hub portion of a spur gear 56, whose pitch circle is substantially of the same diameter as roller 54. Gear 56 meshes with an internal gear 47 formed or mounted within body housing member 48 concentrically with bore 51, and whose pitch circle is substantially of the same diameter as bore 51. a

Each rotor 53 is designed to turn in an orbital path about its raceway 51, with each gear 56 always in mesh with its corresponding internal gear 57, and with inertia roller 54 rolling on the bearing surface afforded by the corresponding raceway bore. To maintain the roller 54 in proper engagement with the raceway surface while the generator is at rest, or coming up to speed, the axle 55 of each rotor is provided with an axial pin 58 which rides around a circular boss 59 projecting inwardly from sidewall 50 on the axis of the corresponding raceway bore.

Generator housing 47 is, as heretofore mentioned, secured to the upper end portion of the bar 41 by means of long screws 46, and as will be seen from FIG. 3 these may be run through the housing member 48 above and below the lower raceway bore 52.

The two rotors 53 are driven through a pair of driveshafts 65 each of which has a universal joint coupling 66 to the corresponding spur gear 56. The shafts 65 are connected through universal joints 67 with gear shafts 68 journalled one above the other in a gear housing 69 on axes which are aligned with the center axes of the raceway bores 51. The upper and lower shafts 68 carry upper and lower gears '70 and 71, which are in mesh with one another, and gear 70 meshes with an idler gear 72, which in turn meshes with and is driven by a gear 73 on the drive shaft 74 of an internal combustion engine designated generally by the numeral 75. The gear housing 69 mentioned above is mounted on a bracket 76 secured to and projecting laterally from mounting block 26, and engine is mounted by means of a supporting frame 7 8 on the upper end of mounting block 26. Engine '75, which may be any suitable internal combustion engine, is shown to have a crankcase 79 provided with an end flange 80 which engages the side of gear housing 69 and is fastened thereto, as indicated.

The operation of the vibration generator is as follows: Rotation of shafts 65, which turn in opposite directions, rolls the two spur gears 56 around the internal gears 57, the'two shafts 65 each moving in a conical gyr-atory fashion. The inertia rollers 54 roll on the surfaces of the cylindrical raceways 51, so that the rotors 53 move in orbital paths. The centrifugal force developed by'the rotors moving in these orbital paths is taken by pressure of the rollers 54 on the surfaces of the raceways 51. The rollers 54 turn at nearly the same rate of rotation as the gears 56, but with some slight variation or creep therebetween, which is accommodated by therotatable mounting of the rollers 54 on the gear shafts 52. The two inertia rotors thus exert gyratory forces on the housing 47. The rotors 53, however, are phased so that the vertical components of their motions will always be equal and opposed, while the horizontal components thereof will be in phase or in step with one another. This is accomplished in the original setting of the rotors by means of the interconnecting gearing. For example, as shown in FIG. 3, the two rotors may be set so that one is at its extreme uppermost position while the other is at its extreme lowermost position. Accordingly, the rotors move up and down with equal and opposed movements, and the vertical components of the reactive forcesexerted thereby on the housing 47 are equal and opposed and cancelled within the housing. On the other hand, the gyrating rotors move horizontally in step with one another, so that the horizontal components of their reactive 'forces exerted against the housing 47 are equal and in phase, and the reactive forces experienced by the, housing 47 are therefore additive in the horizontal direction. The housing 47 therefore exerts an alternating force along a direction line perpendicular to the paper in FIG. 3, and therefore perpendicular to the front edge surface of the bar 41 against which the housing 47 is mounted (FIG. 1).,

The alternating force thus exerted against the bar 41, and which is active to set the latter into a lateral mode of standing wave vibration, is represented by the doubleheaded arrow a in FIG. 1.

It should be observed that the type of vibration generator described and illustrated herein has a desirable frequency step-up characteristic from the drive shafts 65 to the vibratory output force represented by the arrow at, in that for each orbital trip of a given shaft 65 and its corresponding gear 56 and inertia roller 54 around the inside of internal gear 57 and raceway 51, the shaft 65, gear 56 and roller 54 make only a small fraction of a complete revolution on their own axes. The shafts 65 thus gyrate in their conical paths (i.e., make a number of conical circuit trips per second) at substantially greater frequency than their own rotational frequency on their own axes. Thus the orbital frequency of the inertia rotors 54, i.e., the vibration output frequency of the generator housing, is correspondingly multiplied over the rotational frequency of the input driveshafts 65.

It is the objective, as mentioned elsewhere herein, to excite the elastic bar 41 to vibrate in a lateral standing wave mode, and the mode most appropriate is the full wavelength lateral mode represented in the diagram immediately to the left of the bar 41 in FIG. 1. Depending upon the length, lateral dimensions and stiffness of the bar 41, its resonant frequency for attainment of the wave pattern illustrated is typically in the approximate range of to 500 cycles per second, and a frequency of about 300 cycles per second is deemed at present to be illustra trative of a good sonic machine of practical dimensions. The frequency step-up characteristic of the vibration generator disclosed is useful to obtain a vibration frequency of this .order using an internal combustion engine as a prime mover.

With reference further to the standing wave diagram shown immediately to the left of the elastic bar 41 in FIG. 1, the width of the wave pattern at any point represents the amplitude of lateral vibration of the bar 41 at that same level. It will be seen that lateral vibration amplitude is maximized at the upper and lower ends of the bar, and these points are known as velocity antinodes and are designated in the diagram as V and V" respectively. Another velocity antinode V occurs at the midpoint of the bar. Halfway between the midpoint antinode V and the two end point antinodes V and V are velocity nodes N and N, respectively, and these are regions of zero, or minimize-d, vibration .amplitude. These points, which are regions of high acoustic impedance, are advantageous points for pinning of the bar 41 to the mounting block 26 by means of the pins 42, so that the mounting block ears 40 .hold the bar 41 at points of minimized vibration. In the the order of 300 cycles per-second. The vibration amplitude need be but a small fraction of an inch, .but the stress developed as a result of the vibratory action of the relatively heavy bar is very great and the regionof the pavement impinged on the vibrating bar and for some distance therebeyond is subjected to a repetitive stress of such frequency and magnitude as causes it rapidly to fracture and disintegrate.

The operation is started by exposing an edge of the pavement to be cut, and removing the earth for a depth of a few inches therebelow, so as to accommodate the lower end portion of the bar. The tractor is maneuvered into position, with the bar 41 just in back of the paving to be cut, and the mounting block 26 is then lowered, by release of fluid from hydraulic cylinder 37 below .piston 36, until the parts are in the position shown in FIG. 1. The tractor is then driven forwardly to engage the news tic toothedvcoupling face of the bar against the exposed edge of the paving. Engine 75 is driven at a controlled speed to establish resonance in the bar 41, with a Wave action such. as indicated in the diagram and described above. Resonant operation is readily obtained and easily recognize-d by reason of the increased amplitude of vibration at resonance, and particularly by the large changes in amplitude of vibration with small changes in engine speed in the region of resonance.

An important improvement comprises a means for cyclically elevating and lowering the bar '41 through a small fraction'of an inch during its vibratory action, the purpose being to present new area of the paving to the striking teeth 44. This may be accomplished in a number of ways. I here illustrate by way of example, a hydraulic cylinder-90 connected at one end to the hydraulic line 38 leading to the bottom end of hydraulic cylinder 37, a piston 92 in cylinder 90 being reciprocated constantly by means of a connecting rod 93 carrying a 01 lower roller 94 engaged by an eccentric 95 on a shaft 96, which may be driven from any suitable source of power, such as a power take-off shaft of the tractor engine. A suitable gearbox, represented in FIG. 1 at 97,

may connect the eccentric drive shaft 96 with the power takeoff shaft from the tractor engine.

It will be evident that reciprocation of piston 92 in cylinder 90 alternately pumps an increment of hydraulic fluid to and from the lower end of hydraulic cylinder 37, causing a corresponding periodic elevation and lowering of the mounting block 26 and vibratory bar-41 through a predetermined displacement distance.

The bar thus acoustically couples into the exposed edge of the pavement at a predetermined frequency,

and it will be appreciated that the cyclic stress exerted on the pavement is of very great magnitude. Combined with this action is a slower cyclic vertical reciprocation of the entire bar 41, so that the coupling teeth will work up and down across the exposed edge of the pavement to be cut. The cutting or fragmenting action of the vibratory stress so induced in the pavement for some distance ahead proceeds "rapidly, and the vehicle can be driven slowly ahead, cutting a slot in the pavement as it proceeds. In this process, the tractor vehicle moves the bar forwardly against the exposed edge of the pavement, and is of course limited in forward travel by the rate at which'the pavement can be broken. At any given instant, the effort of the tractor vehicle presses the striking face of the bar 41 against the edge of the pavement with a strong forward biasing force. The bar is thereby acoustically coupled to the pavement, and delivers to the pave- .ment a powerful sonic wave which comprises alternate compressions and rarefactions relative to the biasing pres sure. The pavement may be cut or broken away in various ways or in various combinations of ways, depending in large part upon the nature of the paving material. Cement, concrete, or dry asphalt gives way owing to fatigue failure as a consequence of the sonic waves transmitted into it. When these waves reach pressure amplitudes which exceed the endurance limit of the paving material, these materials fail and give way rapidly by elastic fatigue. Pavement may also be broken away by chipping, cutting, or crushing action of the powerfully vibrating toothed coupling face of the bar. Freshly laid asphalt, which might sustain sonic vibrations without fatigue failure, will be simply disintegrated by the power- '-ful sonic wave action delivered from the bar.

made within the scope of the invention as defined by the appended claims.

I claim:

1. Apparatus of the character described for cutting horizontally into a work body of fracturable material,

comprising:

a power-motivated vehicle;

an elastic bar mounted on said vehicle, said bar being elastically vibratory in a pre-determined wave pattern, characterized by regions of substantial vibration amplitude and regions of minimized vibration amplitude, and said bar having, in a region of substantial vibratory amplitude of said wave pattern, a vibratory coupling face oriented for substantially horizontal engagement against, and acoustic coupling to, an exposed surface of said work body upon forward movement of said vehicle;

a vibration generator for so vibrating said bar, said generator being acoustically coupled to said bar in a region of substantial vibration amplitude of said wave pattern;

mounting means for said bar on said vehicle supportingly engaging said bar with minimized vibration transmission of said wave pattern, whereby said vehicle, upon forward movement, acts through said region of minimized vibration transmission to exert a bias force on said bar and said surface of said work body engaged by said coupling face of said bar; and

means for cyclically moving said coupling face of said bar in reverse lateral directions relative to and during said vibration of said bar.

2. The subject matter of claim 1, wherein said means for cyclically moving said coupling face in reverse directions comprises means for cyclically elevating and lowering said coupling face of said bar.

3. The subject matter of claim 1, wherein said coupling face includes a plurality of projections adapted tor working over said exposed face of said work body.

4. Apparatus of the character described for cutting horizontally into a work body of fracturable material, comprising:

a power-motivated vehicle;

an elastic bar mounted on said vehicle in a vertically disposed position, said bar being elastically vibratory in a predetermined lateral wave pattern, in a plane parallel to the direction of travel of the vehicle, and which pattern is characterized by regions of substantial vibration amplitude and regions of minimized vibration amplitude, one of said regions of substantial vibration amplitude comprising the lower end portion of the bar, and there being, on an edge of said lower end portion of said bar, a coupling face oriented for substantially horizontal engagement against and acoustic coupling to an exposed surface of said work body upon forward movement of said vehicle;

a vibration generator for so vibrating said bar acoustically coupled to said bar in a region of substantial vibration amplitude of the wave pattern and arranged for application to the bar of a cyclic force which is parallel to the direction of travel of the vehicle; and

means for mounting said bar on said vehicle in said vertically disposed position, said means engaging the bar in a region of minimized vibration amplitude of said wave pattern, whereby said vehicle, upon forward movement, acts through said region of minimized vibration amplitude to exert a bias force on said bar and the said exposed face of said work body engaged by said coupling face of the bar.

5. The subject matter of claim 4, including means for hoisting said bar relative to said vehicle to an inoperative carrying position spaced above the pavement.

6. The subject matter of claim 4, including a plurality of work engaging projections on said coupling face of said bar.

7. The subject matter of claim 4, including also means for cylically elevating and lowering said bar during vibration thereof whereby to cause said work engaging projections on said bar to progress over the area of the work body opposed thereto.

' 8. The subject matter of claim 4, wherein said vibration generator operates at a frequency to establish a lateral resonant standing Wave in said bar, characterized by at least two vertically spaced velocity nodes;

and wherein said mounting means for said bar supports said bar at each of said two vertically spaced nodes.

9. Apparatus of the character described for cutting horizontally into a work body of fracturable material, comprising:

a power-motivated vehicle;

an elastic bar mounted on said vehicle in a vertically disposed position, said bar being adapted for elastic standing wave vibration in a lateral mode, and in a plane parallel to the direction of travel of the vehicle, with at least two vertically spaced velocity nodes, and at least three velocity antinodes;

a mounting means for said bar engaging said bar at said vertically spaced nodes, so as to avoid interference with said vibration of said bar;

supporting means for supporting said mounting means on said vehicle for movement between an elevated bar carrying position, and a lowered operative position with a lower end portion of said bar positioned pposite an exposed surface of the work. body;

power means for moving said supporting means between said lowered and elevated positions;

a coupling face on the lower end portion of the bar opposed to and engageable with the exposed surface of said work body in said lowered position of said supporting means; and

a vibration generator mounted on said bar in the region of one of said antinodes, so as to apply a cyclic force to the bar in a direction parallel to the direction of travel of the vehicle.

16. The subject matter of claim 9, including also a prime mover for said vibration generator mounted on said mounting means for said bar and drivingly connected to said vibration generator. I

11. The subject matter of claim' 9, including also work engaging projections on said coupling face of'said barf 12. The subject matter of claim 11, including also means for cyclically elevating and lowering'said bar during vibration thereof whereby to cause said working projections on said bar to progress over the exposed surface of the Work body opposed thereto.

13. Apparatus of the character described for cutting horizontally into a work body of fracturable material, comprising: p

a power motivated vehicle having a forward thrust;

an elastic bar mounted on said vehicle, said bar having a working end, and being elastically vibratory with an elastic vibration pattern having'a componenfof vibratory movement oriented in a plane parallel to said thrust, and which pattern is characterizedby a region of substantial vibration amplitude and a region of minimum vibration amplitude, said region of substantial vibration amplitude comprising a region of vibratory coupling with a vibration generator, and there being, on a'lateral edge of said working end of said bar, a toothed cutting element oriented for substantially horizontal engagement against, and acoustic coupling to, an exposed surface of said work body in the direction of said thrust;

a vibration generator for vibrating said bar coupled to said bar at said region of substantial vibration amplitude and being arranged for application to said bar of a cyclic force which has a substantial component parallel to said thrust;

and mounting means for mounting said bar on said vehicle with a minimized degree of acoustic coupling to said bar for minimum transmission of said vibration therefrom, whereby said thrust of said vehicle acts through said mounting means to exert a bias force of said bar against said exposed surface in said direction of thrust of said vehicle. a

14. Apparatus of the character described for cutting into a Work body of fracturable material, comprising:

a power motivated vehicle having a forward thrust,

an elastic bar mounted on said vehicle so as to extend transversely of the direction of said forward thrust, said bar having a working end engageable with said body, and being elastically vibratory with an elastic vibration pattern having a component of vibratory movementoriented in a plane parallel to saidthrust, and which pattern is characterized by a region of substantial vibration amplitude and a region of minimum vibration amplitude, said region of substantial vibration amplitude comprising a region of vibratory coupling with a vibration generator, and there being, on a lateral edge of said working end of said bar, a toothed cutting element oriented for engagement against, and acoustic coupling to, an exposed surface of said work body in the direction of said thrust,

a vibration generator for vibrating said bar coupled to said bar at said region of substantial vibration amplitude; and t mounting means for mounting said bar on said vehicle with a minimized degree of acoustic coupling to said bar for minimum transmission of said vibration therefrom, whereby said thrust of said vehicle acts component of vibratory movement oriented in a- 10 a vibration generator for vibrating said bar coupled to said bar at said region of substantial vibration amplitude and arranged for application to said bar of a cyclic force which has a substantial component through said mounting means to exert a bias force of parallel to said thrust; and

said bar against said exposed surface in said direction mounting means for mounting said bar on said vehicle of thrust of said vehicle. with a minimized degree of acoustic coupling to said 15. Apparatus of the character described for cutting bar for minimum transmission of said vibration thereinto a work body of fracturable material, comprising: from, whereby said thrust of said vehicle acts through a power motivated vehicle having a forward thrust; said mounting means to exert a bias force of said an elastic bar mounted on said vehicle so as to extend bar against said exposed surface in said direction of transversely of the direction of said forward thrust, thrust of said vehicle.

said bar having a working end engageable with said body, and being arranged and mounted for elastic e erences Cited by the Examiner vibration in a lateral vibration pattern having a UNITED STATES PATENTS plane parallel to said thrust, and which pattern is Earshberger 172-40 characterized by a region of substantial vibration 3030715 4/1962 cteymann amplitude and a region of minimum vibration ampli- Bodme' tude, said region of substantial vibration amplitude FOREIGN PATENTS comprising a region of vibratory coupling with a 726,660 10/1942 Germany.

vibration generator, and there being, on a lateral edge of said working end of said bar, a coupling element oriented for engagement against, and acoustic coupling to, an exposed surface of said work body in the direction of said thrust;

CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner. 

1. APPARATUS OF THE CHARACTER DESCRIBED FOR CUTTING HORIZONTALLY INTO A WORK BODY OF FRACTURABLE MATERIAL, COMPRISING: A POWER-MOTIVATED VEHICLE; AN ELASTIC BAR MOUNTED ON SAID VEHICLE, SAID BAR BEING ELASTICALLY VIBRATORY IN A PRE-DETERMINED WAVE PATTERN, CHARACTERIZED BY REGIONS OF SUBSTANTIAL VIBRATION AMPLITUDE AND REGIONS OF MINIMIZED VIBRATION AMPLITUDE, AND SAID BAR HAVING, IN A REGION OF SUBSTANTIAL VIBRATORY AMPLITUDE OF SAID WAVE PATTERN, A VIBRATORY COUPLING FACE ORIENTED FOR SUBSTANTIALLY HORIZONTAL ENGAGEMENT AGAINST, AND ACOUSTIC COUPLING TO, AN EXPOSED SURFACE OF SAID WORK BODY UPON FORWARD MOVEMENT OF SAID VEHICLE; A VIBRATION GENERATOR FOR SO VIBRATING SAID BAR, SAID GENERATOR BEING ACOUSTICALLY COUPLED TO SAID BAR IN A REGION OF SUBSTANTIAL VIBRATION AMPLITUDE OF SAID WAVE PATTERN; MOUNTING MEANS FOR SAID BAR ON SAID VEHICLE SUPPORTINGLY ENGAGING SAID BAR WITH MINIMIZED VIBRATION TRANSMISSION OF SAID WAVE PATTERN, WHEREBY SAID VEHICLE, UPON FORWARD MOVEMENT, ACTS THROUGH SAID REGION OF MINIMIZED VIBRATION TRANSMISSION TO EXERT A BIAS FORCE ON SAID BAR AND SAID SURFACE OF SAID WORK BODY ENGAGED BY SAID COUPLING FACE OF SAID BAR; AND MEANS FOR CYCLICALLY MOVING SAID COUPLING FACE OF SAID BAR IN REVERSE LATERAL DIRECTIONS RELATIVE TO AND DURING SAID VIBRATION OF SAID BAR. 